In the past, a technique of downsize an antenna device by including a parasitic element that performs capacitive coupling with an antenna element is known.
However, in an antenna device according to a related art, in order to further downsize an antenna device, when an antenna element is installed near a substrate, a bandwidth at which impedance matching is made is very narrowed. For this reason, there is a problem in that it is difficult to further downsize an antenna device while securing a bandwidth at which impedance matching is made.